--- a/mercurial/patch.py	Mon Mar 09 13:08:19 2015 -0700
+++ b/mercurial/patch.py	Mon Mar 09 13:09:15 2015 -0700
@@ -862,6 +862,52 @@
     def special(self):
         return util.any(self.special_re.match(h) for h in self.header)
 
+class recordhunk(object):
+    """patch hunk
+
+    XXX shouldn't we merge this with the other hunk class?
+    """
+    maxcontext = 3
+
+    def __init__(self, header, fromline, toline, proc, before, hunk, after):
+        def trimcontext(number, lines):
+            delta = len(lines) - self.maxcontext
+            if False and delta > 0:
+                return number + delta, lines[:self.maxcontext]
+            return number, lines
+
+        self.header = header
+        self.fromline, self.before = trimcontext(fromline, before)
+        self.toline, self.after = trimcontext(toline, after)
+        self.proc = proc
+        self.hunk = hunk
+        self.added, self.removed = self.countchanges(self.hunk)
+
+    def countchanges(self, hunk):
+        """hunk -> (n+,n-)"""
+        add = len([h for h in hunk if h[0] == '+'])
+        rem = len([h for h in hunk if h[0] == '-'])
+        return add, rem
+
+    def write(self, fp):
+        delta = len(self.before) + len(self.after)
+        if self.after and self.after[-1] == '\\ No newline at end of file\n':
+            delta -= 1
+        fromlen = delta + self.removed
+        tolen = delta + self.added
+        fp.write('@@ -%d,%d +%d,%d @@%s\n' %
+                 (self.fromline, fromlen, self.toline, tolen,
+                  self.proc and (' ' + self.proc)))
+        fp.write(''.join(self.before + self.hunk + self.after))
+
+    pretty = write
+
+    def filename(self):
+        return self.header.filename()
+
+    def __repr__(self):
+        return '<hunk %r@%d>' % (self.filename(), self.fromline)
+
 class hunk(object):
     def __init__(self, desc, num, lr, context):
         self.number = num